U.S. patent application number 09/877161 was filed with the patent office on 2002-03-28 for process and apparatus for preparing a composition of matter utilizing a side stream ultrasonic device.
Invention is credited to Franca, Marcos, Maynard, Shawn J..
Application Number | 20020038160 09/877161 |
Document ID | / |
Family ID | 22788149 |
Filed Date | 2002-03-28 |
United States Patent
Application |
20020038160 |
Kind Code |
A1 |
Maynard, Shawn J. ; et
al. |
March 28, 2002 |
Process and apparatus for preparing a composition of matter
utilizing a side stream ultrasonic device
Abstract
The properties of a resinous material product are controlled in
a manufacturing system by online process parameter monitoring and
control. The online monitoring and control incorporates an in-situ
measurement system that can monitor product in the process by use
of a side stream ultrasonic device. The side stream device
advantageously provides online real-time measures of the product's
acoustical properties (e.g. velocity, attenuation) under conditions
that are independent of process-stream conditions. The side stream
device controls the product temperature, pressure, and flow rate
while inside the side stream device and the velocity and
attenuation are measured under these predetermined temperature,
pressure, and flow rate conditions. The acoustical properties (e.g.
velocity, attenuation) of the product, are used to predict the
properties of the product, and provides the process control system
with analysis of the acoustical properties using derived
relationships between the physical properties of the product and
the acoustical properties. Differences between the predicted and
desired product properties are used to control process parameters.
The process can be used for a variety of chemical process
plants.
Inventors: |
Maynard, Shawn J.;
(Angleton, TX) ; Franca, Marcos; (Lake Jackson,
TX) |
Correspondence
Address: |
THE DOW CHEMICAL COMPANY
INTELLECTUAL PROPERTY SECTION
P. O. BOX 1967
MIDLAND
MI
48641-1967
US
|
Family ID: |
22788149 |
Appl. No.: |
09/877161 |
Filed: |
June 8, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60211736 |
Jun 15, 2000 |
|
|
|
Current U.S.
Class: |
700/108 ;
700/109; 700/269; 702/28 |
Current CPC
Class: |
B29C 2948/92104
20190201; G01N 2291/0255 20130101; G01N 29/222 20130101; G01N
2291/015 20130101; G01N 29/4436 20130101; B29C 2948/92514 20190201;
G01N 29/024 20130101; B29C 2948/92704 20190201; B29C 2948/92895
20190201; G01N 2291/102 20130101; G01N 2291/02416 20130101; B29C
2948/92209 20190201; B29C 48/405 20190201; B29C 2948/924 20190201;
G01N 29/032 20130101; B29C 2948/9259 20190201; B29C 2948/922
20190201; G01N 2291/02881 20130101; B29C 48/9185 20190201; B29C
48/92 20190201; B29C 48/625 20190201; G01N 29/30 20130101; B29C
2948/92019 20190201; B29C 2948/926 20190201 |
Class at
Publication: |
700/108 ;
700/269; 700/109; 702/28 |
International
Class: |
G06F 019/00 |
Claims
What is claimed is:
1. A process for online monitoring and control of a process plant
having a plurality of steps producing a product with a property P
having a desired value D, comprising the steps of: (a) providing a
side stream flow of the product to be measured, (b) online
measuring at least one property P of the product by propagating an
ultrasonic wave through said side stream product, and (c) in view
of the result of the measurement made in step (b) controlling the
preparation of the product by controlling certain process
parameters.
2. The process of claim 1 including the step of comparing the
product property P to a desired predetermined property D.
3. The process of claim 1 wherein the product property P is derived
by (i) measuring the ultrasonic properties such as velocity,
temperature, pressure, and attenuation; and (ii) correlating these
properties to the product properties by mathematical algorithms
which were derived by correlation between standard materials and
ultrasonic parameters.
4. The process of claim 3 wherein a product property P' is derived
by correlating the measured product property P by mathematical
algorithms which were derived by correlation between standard
materials for product properties P' and measured product property
P.
5. The process of claim 3 wherein the product property P is derived
by controlling the flow rate, pressure or temperature of the side
stream.
6. A process for preparing a composition of matter comprising the
steps of: (a) feeding one or more components of a composition of
matter into a continuous reactor, (b) preparing a composition of
matter from the one or more components in the reactor, (c)
providing a side stream flow of the composition of matter product
to be measured, (d) measuring at least one property of the
composition of matter by propagating an ultrasonic wave through
said side stream of composition of matter, and (e) in view of the
result of the measurement made in step (d), controlling the
preparation of the composition of matter within the reactor.
7. The process of claim 6 wherein the side stream in step (c) is
provided at a consistent flow rate, pressure and temperature or at
a controlled rate of change of flow rate, pressure and temperature
to an ultrasonic measuring means.
8. The process of claim 6 wherein the reactor is an extruder.
9. The process of claim 6 wherein the composition of matter is a
resinous material.
10. The process of claim 9 wherein the resinous material is a
polymer.
11. The process of claim 10 wherein the polymer is an epoxy.
12. A process for preparing a polymer comprising the steps of: (a)
feeding one or more monomers and/or oligomers into a continuous
reactor, (b) forming a polymer by polymerizing the one or more
monomers and/or oligomers within the reactor, (c) providing a side
stream flow of the polymer, (d) measuring at least one property of
the polymer by propagating an ultrasonic wave through said side
stream of polymer, (e) in view of the result of the measurement
made in step (d), adjusting and/or maintaining at least one
condition that affects the polymerization of the one or more
monomer(s) and/or oligomer(s) within the reactor so as to control
the resultant polymer, and (f) recovering from the reactor the
polymer prepared after the adjustment and/or maintenance of the
condition performed in step (e).
13. The process of claim 12 therein the reactor is an extruder.
14. The process of claim 12 wherein the measurement step (d) is
carried out during the polymerization of the one or more monomers
and/or oligomers; and/or after the polymer is formed.
15. The process of claim 12 wherein the property measured in step
(d) is at least one member selected from the group comprising
viscosity, melt index, melt flow rate, molecular weight, molecular
weight distribution, equivalent weight, phenolic OH, conversion,
blend composition, additive composition, morphological composition,
phase distribution, domain size, particle size, particle size
distribution, melting point, viscoelastic properties (for example,.
G', G", Tan Delta), glass transition temperature, density, specific
gravity, thermodynamic constants, and purity.
16. The process of claim 12 wherein the condition of the
polymerization that is adjusted and/or maintained is at least one
member selected from the group comprising: rate of feed of the
monomer(s) and/or oligomer(s), temperature of monomer and/or
oligomer feeds, catalyst concentration, stoichiometry, reaction
temperature, heating rate of the extruder, cooling rate of the
extruder, screw speed, extruder size, extruder throughput, screw
design, resident time distribution, rate of mixing, degree of
mixing, rate of reaction and length of reaction time.
17. The process of claim 15 wherein the property measured is
viscosity.
18. The process of claim 12 including the step of determining the
presence of a contaminant in the polymer prepared in step (b) by
ultrasonic waves.
19. The process of claim 18 wherein the extent of the presence of
the contaminant in the polymer is quantified by ultrasonic
waves.
20. The process of claim 12 further comprising the step of feeding
a catalyst to the reactor.
21. The process of claim 12 including the steps of: (g) conveying
polymer from the reactor to a mixer, through a connection between
the reactor and the mixer, polymer(s) prepared after the adjustment
and/or maintenance of the condition performed in step (e), and (h)
preparing a composition of matter by admixing, in the mixer, one or
more other components of the composition of matter with the
polymer(s) prepared in step (b).
22. The process of claim 21 wherein the mixer is an extruder.
23. An apparatus for online monitoring and control of a process
plant having a plurality of steps producing a product with a
property P having a desired value D comprising: (a) a means for
providing a side stream of the product, (b) an ultrasonic means for
online measuring at least one property P of the product by
propagating an ultrasonic wave through said side stream product,
(c) a means for comparing the product property P to a desired
predetermined property D, and (d) a means for controlling the
preparation of the product by controlling certain process
parameters based on the in view of the result of the measurement
made by the ultrasonic means in (a) and the comparison made by the
comparison means in (b).
24. An apparatus for preparing a composition of matter comprising:
(a) a means for feeding one or more components of a composition of
matter into a continuous reactor, (b) a continuous reactor for
preparing a composition of matter from the one or more components
fed to in the reactor, (c) a means for providing a side stream of
the composition of matter, (d) an ultrasonic wave measuring means
for measuring at least one property of the side stream of the
composition of matter, and (e) a means for controlling the
preparation of the composition of matter within the reactor based
on the result obtained by the measurement means in (d).
25. An apparatus for preparing a polymer comprising: (a) a means
for feeding one or more monomers and/or oligomers into a continuous
reactor, (b) a continuous reactor for forming a polymer by
polymerizing the one or more monomers and/or oligomers, (c) a means
for providing a side stream of the polymer, (d) an ultrasonic wave
measuring means adapted for propagating ultrasonic waves through
the side stream of the polymer and for measuring at least one
property of the side stream, (e) a means for adjusting and/or
maintaining at least one condition that affects the polymerization
of the one or more monomer(s) and/or oligomer(s) within the reactor
based on the result obtained by the measurement means in (d), and
(f) a means for recovering from the reactor the polymer prepared
after the adjustment and/or maintenance of condition is made by the
means of (e).
26. The apparatus of claim 25 wherein the reactor is an
extruder.
27. The apparatus of claim 25 wherein the measurement means of (d)
is adapted for measuring the at least one property of the polymer
during the polymerization of the one or more monomers and/or
oligomers; and/or after the polymer is formed.
28. The apparatus of claim 25 wherein the property measured is at
least one member selected from the group comprising viscosity, melt
index, melt flow rate, molecular weight, molecular weight
distribution and equivalent weight.
29. The apparatus of claim 25 wherein the condition of the
polymerization that is adjusted and/or maintained is at least one
member selected from the group comprising: rate of feed of the
monomer(s) and/or oligomer(s), catalyst concentration,
stoichiometry, reaction temperature, rate of mixing, degree of
mixing, rate of reaction and length of reaction time.
30. The apparatus of claim 20 including an ultrasonic wave
measuring means for determining the presence of a contaminant in
the polymer.
31. The apparatus of claim 30 wherein the ultrasonic wave measuring
means is adapted for quantifying the presence of the contaminant in
the polymer.
32. The apparatus of claim 29 further comprising a means for
feeding a catalyst to the reactor.
33. An apparatus of claim 25 including: (g) a mixer connected to
the reactor, said mixer adapted for preparing the composition of
matter by admixing, the polymer(s) prepared in the reactor with one
or more other components of the composition of matter, and (h) a
means for conveying from the reactor to the mixer, through a
connection between the reactor and the mixer, the polymer(s)
prepared after the adjustment and/or maintenance of condition
performed in (e).
34. The apparatus of claim 33 wherein the mixer is an extruder.
Description
BACKGROUND OF THE INVENTION
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/211,736, filed Jun. 15, 2000.
[0002] This invention relates to a chemical plant and to a process
and apparatus for controlling chemical processes in a chemical
plant. More specifically, the present invention relates to a
process and apparatus for controlling the reaction process of a
composition of matter such as a solid epoxy resin product,
utilizing a side stream sample of the product stream and a side
stream ultrasonic measuring device. The reaction process is
controlled, for example by controlling certain parameters such as
epoxy equivalent weight, molecular weight, molecular weight
distribution, or viscosity of the solid epoxy resin product.
[0003] A prominent method for controlling the process of
polymerizing monomers or oligomers into higher oligomers or
polymers involves sampling and off-line measuring polymer
properties, such as epoxy equivalent weight, phenolic OH, or
viscosity. These off-line measurement results, in combination or
separately, are then used as the variables by which the entire
process is controlled.
[0004] These off-line measurements are time consuming, expensive,
and require material to be removed from the process. Process
constraints may prohibit the sampling of material and the time
requirements for obtaining the measurements are long enough to make
controlling the process by these off-line methods problematic,
expensive, and prohibit process automation.
[0005] Furthermore, there are certain desired product property
measurements that can not be made under process conditions in the
product stream, such as viscoelastic and thermodynamic
measurements. Currently, these measurements are made off-line after
the product has been cooled and the measurements are performed
under specific sample temperature conditions, where the sample may
be heated to a specific isothermal temperature or the sample may be
heated at a specific rate from one temperature to another. In many
cases, prior to these measurements being made the product will have
been reformed into shapes acceptable for the specific measuring
device, for example by compression molding machines. These tests
are time consuming and expensive, requiring in many cases the
product to be quarantined until test results are obtained. The
results of the tests qualify the material as good or bad. However,
the production of bad product typically can not be changed because
of the time involved in generating the product property data
prohibits an active feedback to the process control loop.
[0006] A need exists for an on-line technology that enables process
automation by providing real-time, efficient, and precise polymer
measurements of the product independent of processing conditions,
such as temperature, that can be used as process control
parameters.
[0007] Repetitious sampling and analytical measurements applied to
a chemical production process present several significant potential
problems.
[0008] First, there is inherent danger of removing a sample from a
hot process stream, especially when the stream is viscous as in a
polymer-forming process. Large insulated valves must be opened to
allow material to flow into a small sample container. It is not
uncommon for sampling ports in polymer lines to become partially
plugged, causing the hot material to be unpredictably expelled from
the opening.
[0009] Second, the procedure of removing a sample may alter the
sample constitution. For example, the material removed from the
line may only be partially converted and continue to react in the
sample container after it is removed from the line. Furthermore, as
the sampled material is viscous, it clings to the sample port
valve, which may cause the current sample to be intermixed with
remnants of previously acquired samples.
[0010] Third, the sampling and analysis procedure is time
consuming. Many hundred or thousands of pounds of material can be
produced in the time required to remove, prepare, and analyze a
sample. The analytical data obtained from the sample is therefore
of limited value for proactive process control.
[0011] Finally, because of the difficulties, cost, and hazards
associated with sample removal, analytical sampling is typically
infrequent. With minimal analytical data points, it is difficult to
gain a statistically valid understanding of process variations or
to make proper control adjustments to the process.
[0012] A preferred analysis method would monitor the material as it
is being produced. Such a method would reduce the need to remove
samples from the production environment, diminish the safety
concerns, and facilitate more frequent and faster measurements.
[0013] There are, however, challenging obstacles that prevent most
analytical techniques from providing in situ, on-line chemical
constitution information in a process environment. First, the
analytical method must be capable of accurately determining the
desired properties with sufficient precision. Second, the
analytical instrument must either be capable of withstanding the
physical environment of a processing area or must be capable of
sensing the desired composition properties from a remote location.
Third, the interface of the instrumentation with the process must
be able to survive the harsh pressure and temperature environment
found inside the chemical process lines. Fourth, turbidity, bubbles
and other common processing phenomena must not disturb the
analytical measurements.
[0014] It is therefore desired to provide a process and apparatus
that will overcome all of the above obstacles of the prior art
methods and apparatuses.
SUMMARY OF THE INVENTION
[0015] One aspect of the present invention is directed to a process
for online monitoring and control of a process plant having a
plurality of steps producing a product with a property P having a
desired value D including (a) providing a side stream flow of the
product to be measured, (b) online measuring at least one property
P of the product by propagating an ultrasonic wave through said
side stream product, (c) comparing the product property P to a
desired predetermined property D, and (d) in view of the result of
the measurement made in step (b) and the comparison made in step
(c), controlling the preparation of the product by controlling
certain process parameters.
[0016] Another aspect of the present invention is directed to an
apparatus for online monitoring and control of a process plant
having a plurality of steps producing a product with a property P
having a desired value D including (a) a means for providing a side
stream of the product to be measured, (b) an ultrasonic means
adapted for propagating an ultrasonic wave through said side stream
product and for online measuring at least one property P of the
side stream product, (c) a means for comparing the product property
P to a desired predetermined property D, and (d) a means for
controlling the preparation of the product by controlling certain
process parameters based on measurement data made by the ultrasonic
means of (b) and comparison data made by the comparison means of
(c).
[0017] Still another aspect of the present invention is directed to
a process for preparing a composition of matter comprising the
steps of:
[0018] (a) feeding one or more components of a composition of
matter into a continuous reactor,
[0019] (b) preparing a composition of matter from the one or more
components in the reactor,
[0020] (c) providing a side stream flow of the composition of
matter product to be measured,
[0021] (d) measuring at least one property of the composition of
matter by propagating an ultrasonic wave through said side stream
of composition of matter, and
[0022] (e) in view of the result of the measurement made in step
(d), controlling the preparation of the composition of matter
within the reactor.
[0023] Yet another aspect of the present invention is directed to
an apparatus for preparing a composition of matter comprising:
[0024] (a) a means for feeding one or more components of a
composition of matter into a continuous reactor,
[0025] (b) a continuous reactor for preparing a composition of
matter from the one or more components in the reactor,
[0026] (c) a means for providing a side stream of the composition
of matter,
[0027] (d) an ultrasonic wave means for measuring at least one
property of the side stream of the composition of matter by
propagating an ultrasonic wave through said side stream of the
composition of matter, and
[0028] (e) a means for controlling the preparation of the
composition of matter within the reactor based on the result of the
measurement made by the ultrasonic wave means of (d).
DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a simplified flow diagram of a plant for
manufacturing a resinous material.
[0030] FIG. 2 is a schematic representation, partly in cross
section, of one embodiment of the process and apparatus of the
present invention, and in particular, illustrates a side stream
ultrasonic analyzer system used in the process of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] In general, the process of the present invention comprises
an online monitoring and control process for a chemical plant
having a plurality of steps producing a product with a property P
having a desired value D utilizing a side stream ultrasonic waves
means for measuring a property P of the side stream product and
then based on the measurement controlling certain parameters of the
process to obtain the desired value D of the product.
[0032] Generally, the process of the present invention is directed
to controlling a reaction process for producing a product. The
product may be any chemical product and preferably is a resinous
material; and more preferably, the resinous material is a polymer
resin.
[0033] The polymer resin useful in the present invention is
preferably prepared by polymerizing one or more monomers and/or
oligomers to form the polymer. As will be described below with
reference to the Figures, the polymer resin is preferably prepared
in a continuous reactor extruder.
[0034] The present invention is best understood by reference to the
accompanying FIGS. 1 and 2 illustrating the preferred embodiments
of the present invention.
[0035] FIG. 1 illustrates one embodiment of the present invention
and shows a simplified flow chart of a manufacturing process for
the production of a resinous product such as an epoxy resinous
product. With reference to FIG. 1, a resinous product, such as an
epoxy resin, is typically manufactured by reacting epoxy monomers
or oligomers to higher oligomers or polymers by action of a
nucleophilic agent.
[0036] The process, shown in FIG. 1, is typically performed by
blending or mixing a feed of one or more components such as epoxy
monomers or oligomers with a nucleophic agent, a catalyst and,
optionally, other additives or chain terminating agents in a mixing
vessel or reactor 11. The mixture is typically heated in the
reactor 11 and allowed to react for a period of time, until the
desired product properties are achieved. The final properties of
the product are measured by taking a side stream of the product
stream utilizing a side stream ultrasonic analyzer system 12 and
programmable logic controller 13. Preferably, the product may be
purified and/or conditioned before measurement. Then the product
may be either delivered to another process for further
modification, or transformed into a form suitable for final
distribution and sale as shown in product distribution means
14.
[0037] The final product properties are compared to the desired
product properties to adjust product parameters in 13, as
illustrated in FIG. 1, with a control loop in order to maintain the
desired product properties. Also, the final product property
measurements may be stored for statistical quality control
records.
[0038] In operation, the ultrasonic control means apparatus
indicated as numeral 12 in FIG. 1 (also generally indicated as
numeral 20 in FIG. 2) propagates ultrasonic pulses through a
product that is located between two surfaces in a direction normal
to the flow. The ultrasonic pulses have duration such as to prevent
successive echoes from overlapping with one another while
reverberating between the two surfaces. The surface that the sound
emanates from initially is the transmitter and the other surface is
the receiver. The ultrasonic sound propagates from the transmission
surface through the product and into the receiver surface,
generating the through transmission signal (A.sub.0). The first
echo signal (A.sub.1) is generated when the sound reflects off the
receiver surface back into the product, reflecting off the
transmission surface back into the product, and into the receiver
surface.
[0039] Depending on the product, this echo or reverberation process
may continue, generating successive echo signals (A.sub.2, A.sub.3.
. . ). The delay time between two successive signals is
continuously monitored to provide output signals representative of
the product ultrasonic velocity. The amplitude difference between
two successive signals is continuously monitored to provide output
signals representative of the product ultrasonic attenuation. At
the same time the temperature and pressure of the product is
continuously monitored to provide output signals representative of
the product temperature and pressure. These output signals are
processed as a function of time to generate quantitative
information relating to the product properties, P. This product
property is compared to the desired property, D, to control process
parameters.
[0040] FIG. 2 illustrates an ultrasonic side stream apparatus 20
useful in the present invention for online monitoring of a flow
stream in a manner that enables a prediction of the properties of
the finished product independent of processing conditions. The
ultrasonic side stream apparatus 20 of the present invention
provides for the diversion of product from the main process stream
to provide online monitoring of a flow stream in a manner that
enables a prediction of the viscoelastic, thermodynamic properties,
epoxy equivalent weight, molecular weight, molecular weight
distribution, viscosity, or melt index of the product. This
prediction is, in turn, used to manipulate the inputs and the
operating conditions of the process equipment to obtain finished
products with the desired properties.
[0041] With reference to FIG. 2, there is shown an ultrasonic side
stream device, generally indicated by numeral 20, coupled to a
process flow stream 30 flowing in the direction indicated in arrow
31 in conduit 32. The device 20 comprises a sampling port 33, a
gear pump 34, a product-conditioning zone, generally indicated by
numeral 40, and an ultrasonic measurement cell, generally indicated
by numeral 50. The gear pump 34 provides consistent precision flow
rates and pressure; and the product-conditioning zone 40 delivers
product to the ultrasonic measurement cell 50 at a consistent
temperature. The product temperature may be constant or a
temperature ramp where the initial temperature, final temperature,
and rate of temperature increase or decrease is predetermined for
the type of measurements needing to be made. The product pressure
may be constant or a pressure ramp where the initial pressure,
final pressure, and rate of pressure increase or decrease is
predetermined for the type of measurements needing to be made. The
product flow rate may be constant or a flow rate ramp where the
initial flow rate, final flow rate, and rate of flow increase or
decrease is predetermined for the type of measurements needing to
be made.
[0042] Again with reference to FIG. 2, one preferred embodiment of
the ultrasonic measurement cell 50 of the present invention is
described including a temperature measurement device 51, a pressure
measurement device 52, a transmission buffer rod 53, a transmission
ultrasonic transducer 55, a receiver buffer rod 54, a receiver
ultrasonic transducer 56, and a ultrasonic analyzer assembly 57
with electrical leads 58 and 59.
[0043] In the preferred embodiment, the ultrasonic analyzer
assembly 57 includes cables, a pulser, a receiver, a waveform
digitizer, a signal processor, a data processor, and a process
computer, not shown, which are well known to those skilled in the
art.
[0044] In a typical application the pulser in the assembly 57 sends
out an ultrasonic pulse to the transducer 55 where the electronic
signal is transformed into a mechanical ultrasonic sound wave
emanating from the transducer 55 and into the transmission buffer
rod 53, traveling down the buffer rod 53 and into the product flow
stream 35 in fluid passageway 41, where the sound wave is
transmitted into the receiver buffer rod 54, and then transformed
back into an electronic signal at the receiver ultrasonic
transducer 56, where the electronic signal is transmitted back to
the polymer analyzer system 57 on a receiver channel. This analog
signal is received, digitized, processed, and results in velocity
and attenuation measurements C.
[0045] In conduit 32, product 30 is shown flowing in the direction
indicated by arrow 31. A portion of the product, indicated by arrow
35, flowing through the process stream 30 is diverted into the
ultrasonic side stream device 20 through the sampling port 33 where
the gear pump 34 forces the product portion 35 toward and through
the product-conditioning zone 40. The section 40 is preferably a
fluid passageway 41 having an inlet 42 and an outlet 43. The
section 40 may also include a series of static mixers (not shown)
inserted in the passageway 41 located inside of a temperature
regulated housing 44. The side stream product portion 35 then
passes from the outlet 43 to the ultrasonic measurement cell 50. In
the cell 50, the side stream 35 passes between two buffer rods 53
and 54, after which the side stream product is returned back to the
process stream 30 via another sampling port 36.
[0046] The ultrasonic side stream device 20 also includes a
temperature-measuring device 51 that comprises a probe that
monitors the temperature of the side stream product. The output of
the temperature measurement device is a temperature measurement T
of the side stream product temperature. The temperature measurement
is used by the process computer, not shown, as described below.
[0047] The ultrasonic side stream device 20 also includes a
pressure-measuring device 52 that comprises a probe that monitors
the pressure of the side stream product. The output of the pressure
measurement device is a pressure measurement P.sub.1 of the side
stream product pressure. The pressure measurement is used by the
process computer, not shown, as described below.
[0048] The outputs C, T, and P.sub.1 of the ultrasonic instrument
assembly 20 are transmitted to a computer that analyzes the
measurements, as discussed below, and predicts the product 30
properties that could be expect from the process. Difference
between the predicted product properties, P, and the desired
properties, D, of the product 30 are used to control the process
parameters, also as discussed below.
[0049] The side stream device shown in FIG. 2 is for illustrative
purpose only. Those knowledgeable in the art would recognize other
measurements or designs could be incorporated in the device
described above. These additional measurements or designs are
intended to be within the scope of the present invention.
[0050] The ultrasonic side stream device 20 is generally mounted so
as to monitor a side stream of a product flow stream, for example
an epoxy resin. The device 20 may be disposed to divert a sample
from the reactor itself or at any point downstream of the reactor
11. For example, the device 20 may be positioned so as to obtain a
portion of the flow stream directly after the product exits the
reactor 11. In another embodiment of the present invention, the
mounting of the device may be done at the output of another step in
the process, for example after a purification step in the process.
The measurements using the side stream device 20 are used to
determine, for example, the epoxy equivalent weight, molecular
weight, molecular weight distribution, viscosity, or melt index of
the epoxy product.
[0051] The components of the ultrasonic instrumentation assembly 50
including for example, the temperature measuring device 51, the
pressure measuring device 52, buffer rods 53 and 54, ultrasonic
transducers 55 and 56, and analyzer assembly 57, are not discussed
in detail as these components would be familiar to those
knowledgeable in the art.
[0052] As described above, the propagating sound wave can be
transmitted or reflected, generating the signals of interest
(A.sub.1, A.sub.2, A.sub.3. . . ). These signals are amplified,
digitized, and processed through a correlation procedure such as
described and incorporated herein by reference William H. Press et
al., in Numerical Recipes, pages 381-416, to obtain data comprising
ultrasonic velocity and attenuation values measured simultaneously
as a function of time.
[0053] The propagating sound wave can be transmitted or reflected,
generating the signals of interest (A.sub.1, A.sub.2, A.sub.3. . .
) from which the measurements of velocity and attenuation are made
(A.sub.2-A.sub.1, A.sub.3-A.sub.2, etc.), as described in U.S. Pat.
No. 5,433,112, incorporated by reference, particularly with
reference to FIG. 2.
[0054] The delay time between two successive signals
(A.sub.2-A.sub.1, A.sub.3-A.sub.2, etc.) is continuously monitored
to provide output signals representative of the product ultrasonic
velocity. The amplitude difference between two successive signals
is continuously monitored to provide output signals representative
of the product ultrasonic attenuation. These two acoustical
measurements are for illustrative purpose only. Those knowledgeable
in the art would recognize that other measurements could be also
made using the signals described above. These additional
measurements are intended to be within the scope of the present
invention.
[0055] A reactor with an inlet and an outlet is preferably used for
producing a polymer in the present invention. At least one or more
reactant components are fed into the reactor from a feeding means.
A reaction occurs within the reactor and the reaction in the
reactor is controlled with an ultrasonic side stream control means
20. A product stream exits the reactor at the outlet of the
reactor. The composition of matter prepared in the reactor, is
generally a resinous material; and more specifically, the resinous
material is a polymer resin. The resinous material useful in the
present invention is prepared by using a continuous reactor 30. The
continuous reactor 30 used for this purpose may be a pipe or
tubular reactor, or an extruder. It is preferred to use an
extruder. More than one such reactor may be used for the
preparation of different resinous materials. Any number of reactors
may be used in the present invention.
[0056] The polymer resin useful in the present invention is
preferably prepared by polymerizing one or more monomers and/or
oligomers in the continuous polymerization reactor to form the
polymer. Typically, a catalyst may be added to the polymerization
reaction mixture for the purpose of obtaining a specific type of
resinous material, or a desired rate of conversion. The monomer(s),
oligomer(s), and catalyst when desired, may, each separately or in
groups of two or more, be fed to the polymerization reactor in one
or more of the following forms: a liquid solution, a slurry, or a
dry physical mixture.
[0057] The resinous material from which a composition is prepared
may be virtually any polymer or copolymer. The resinous material
need not have any particular molecular weight to be useful as a
component in the composition. The resinous material may have
repeating units ranging from at least two repeating units up to
those resinous materials whose size is measured in the hundreds or
thousands or repeating units. Particular resinous materials that
may be used in the methods of the present invention include for
example, epoxy resins, polyesters, urethanes, acrylics and others
as set forth in U.S. Pat. No. 5,094,806 which is incorporated
herein by reference.
[0058] The most preferred resinous materials useful in the present
invention from among those listed above are epoxy resins and
polyesters. Epoxy resins useful in the present invention, and
materials from which epoxy resins may be prepared, are described in
U.S. Pat. No. 4,612,156, which is incorporated herein by reference.
Polyesters useful in the present invention, and materials from
which polyesters may be prepared, are described in Volume 12 of
Encyclopedia of Polymer Science and Engineering, pages 1-313 which
pages are incorporated herein by reference. A most preferred
resinous material prepared according to the present invention may
be the reaction product of an epoxy resin and bisphenol A to form a
higher oligomer or polymer.
[0059] In the production of a resinous material to be used in the
present invention, various conditions or parameters have an effect
on the course of the polymerization reaction. Typical examples of
these conditions or parameters are as follows: the rate of feed to
the reactor of the monomer(s) and/or oligomer(s); the temperature
at which the reaction occurs; the length of time during which the
reaction occurs; and the degree to which the reactants are mixed or
agitated before or during the reaction. The rate of feed of
monomer(s) and/or oligomer(s) can be influenced, for example, by
valve adjustment on a pressured line. The temperature at which the
reaction occurs can be influenced, for example, by the direct
heating or cooling of the monomer(s) and/or oligomer(s) or to the
reactor itself. The length of time during which the reaction occurs
can be influenced, for example, by the size of the reactor, such as
the length of a pipe, tube or extruder, or the speed at which the
reactants move into and out of the reactor, such as may result from
the particular speed or design of an extruder screw, or the
introduction of a pressurized inert gas into a pipe or tube. The
degree to which the reactants are mixed or agitated during the
reaction can be influenced, for example, by the size, shape and
speed of blades or other mixing elements, by the presence of a
static mixing element in a pipe or tube, or the speed of the screw
in an extruder.
[0060] The quality of the composition that may be prepared by the
process of the present invention is improved if the properties of
the resinous material are known and maintained at a desired level.
Typical examples of resinous material properties that may be
analyzed for this purpose are viscosity, melt index, melt flow
rate, molecular weight, molecular weight distribution, equivalent
weight, phenolic OH, conversion, blend composition, phase
distribution, domain size, particle size, particle size
distribution, melting point, viscoelastic properties (e.g. G', G",
Tan Delta), glass transition temperature, density, specific
gravity, and purity. For example, when an epoxy resin is used as a
resinous material, it is desired that its viscosity be in the range
of from about 1 to about 100,000 centipoise.
[0061] The analytical technique that is used to determine resinous
material properties such as the foregoing include ultrasonic wave
energy utilizing the ultrasonic side stream control means 20, shown
in FIGS. 1 and 2, of the present invention.
[0062] Polymeric properties P such as those mentioned above may be
maintained at a desired level by adjusting one or more of
conditions or parameters that have an effect on the course of the
polymerization reaction. Typical examples of such conditions or
parameters are discussed above. To determine the manner and extent
to which polymerization conditions should be adjusted, however, the
analytical technique must first be performed to determine to what
extent, if any, the polymeric property differs from the desired
level.
[0063] A particularly advantageous method of using polymeric
property data in connection with the adjustment of polymerization
conditions is to perform the analysis needed to determine the
polymeric properties of interest while the polymerization reaction
is in progress. This method involves performing the property
analysis on polymer or copolymer that is actually inside the
reactor.
[0064] In one embodiment, the required analytical instrument
extracts a sample from inside the reactor such that the polymer or
copolymer side stream sample passes through the side stream
instrument for analysis as the reaction progresses in that vicinity
of the reactor. It is also preferred to perform property analysis
on a polymer prior to the point of its exit from the reactor or as
the polymer exits the reactor.
[0065] After the polymeric property data has been obtained by
analyzing the side stream as it relates to a polymer or copolymer
that is inside the reactor, an adjustment in one or more conditions
of the reaction may be made if necessary. Adjusting the conditions
under which a polymer is prepared, in response to an analysis (as
the polymer is being prepared) of the properties of the polymer
resulting from those conditions, enables real-time control of the
reaction by which the polymeric component or a blended composition
is prepared.
[0066] The polymeric material needs to have specific physical and
thermodynamic properties to be useful as a component in the
composition. The reacting monomeric mixture as well as the
polymeric material must be measured to achieve and maintain the
physical and thermodynamic properties of the polymeric material.
Sampling the material is a significant problem. This measurement
could be made off-line by sampling the reacting monomeric mixture
or polymeric material; however, this approach is less desirable
than real-time on-line analysis of the reacting monomeric mixture
and polymeric material. For example, off-line analyses are less
accurate because the material continues to react after removal from
the mixer. Furthermore, the time it takes to perform the off-line
analysis, is time that the process could potentially be operating
outside of its "normal" range. On-line measurements of physical and
thermodynamic properties are not burdened by these issues and
real-time analysis eliminates the time lag between measurement
observation and process response.
[0067] The on-line measurement of the present invention is
preferentially made by use of ultrasonic sound waves after
propagation through a side stream of the monomeric mixture or
polymeric material. For example, acoustic sound waves are
propagated through the monomers, monomeric mixture, or polymeric
material where the acoustic characteristics (velocity, attenuation,
amplitude, frequency, or phase shift) are altered by interaction
with such material. This change in acoustic character is related to
the physical and thermodynamic properties of the monomers, reacting
monomeric mixture, higher oligomers, or polymeric material and
gives rise to the measurement of such properties. By using standard
materials, mathematical algorithms are derived that describe the
interaction between the acoustic parameters and the product
properties P. The mathematical algorithm is used to derive the
product properties P by measuring the acoustic properties.
Furthermore, additional algorithms can be used to derive other
product properties P' from product properties P.
[0068] These physical and thermodynamic property measurements P or
P' constitute the process output of the ultrasonic device. These
properties are achieved and maintained by means of controlling key
process variables by using the process output from the ultrasonic
device. The output of the ultrasonic device is used by the process
control code, which decides which process variable(s) are altered
and to what degree in order to maintain the physical and
thermodynamic properties of the reacting monomeric mixture or
polymeric material. For example, appropriate adjustments could be
made to the mixing rate, reactor pressure, reactor temperature,
monomer and/or catalyst feed temperatures, monomer and/or catalyst
feed ratios, mixer design, or reactor design.
[0069] For example, when an epoxy resin is being made in a reactor,
it is helpful to measure one or more properties such as viscosity,
molecular weight or epoxy equivalent weight. If the property
measured does not have a value within the desired range, an
adjustment may be made to one or more of the conditions of
polymerization such as the rate of feed of the reactants, the
temperature at which the reaction occurs, or the length of the
duration of the reaction. When the reaction is being conducted in a
pipe or tubular reactor or an extruder, the length of the duration
of the reaction may be controlled by regulating the force with
which the reactants are moved through the reactor, for example the
force with which originally fed to the reactor or the speed of the
screw in an extruder.
[0070] When one or more properties of an epoxy resin such as
viscosity, molecular weight, epoxy equivalent weight or content of
contaminants is being measured, it is particularly useful to
perform such measurements by the propagation of ultrasonic pulse
through the epoxy resin. Methods for the use of ultrasonic pulses
to measure the properties of polymers are described in U.S. Pat.
Nos. 4,754,645 and 5,433,112; each of which is incorporated by
reference in its entirety into this application.
[0071] In another embodiment of the present invention, a
composition comprising a mixture or a blend of two or more
components may be prepared. For example, the resinous material may
be prepared in one reactor, as one component of the final
composition, and then the resinous material may be combined with
one or more other resinous materials or with one or more other
ingredients or additives. The resinous material prepared in the
reactor may be continuously conveyed from the reactor to a mixer
through a connection between the reactor and the mixer.
[0072] If more than one reactor is used, a connection is
established between each reactor and the mixer. Optionally, a
blended or compounded composition may be prepared by feeding the
exit product stream from several reactors connected directly to a
mixer in which the blended or compounded composition is prepared. A
pipe or tubular joint is suitable for use as the means of making
the connection between the reactor and the mixer.
[0073] The preferred type of mixer used in the present invention,
is an extruder, particularly a twin-screw extruder but other types
of mixers such as co-kneaders may be used as well.
[0074] As aforementioned, a composition may be prepared by
compounding the resinous material with other components of a
composition. The other components of the composition includes a
number of other ingredients which may also include another resinous
material, such as an epoxy or a polyester, or other resinous
materials listed above. The remaining components of the composition
may also include ingredients such as conventional additives for
example hardeners for an epoxy resin (e.g. dicyandiamide), fillers,
pigments, stabilizers and other additives well known in the art.
Other additives as ingredients for the composition of the present
invention are disclosed in U.S. Pat. No. 5,416,148 which is
incorporated herein by reference. Such additives may be
incorporated as a liquid into the composition. After mixing the
composition in the mixer, the composition is recovered in a form
suitable for handling, such as in the form of a flake or
pellet.
[0075] Other materials which can be measured according to the
present invention may include for example, polyurethanes, epoxy
thermoplastics such as PHAE and PHEE, liquid epoxy resins such as
DER*331 and DER 383 as well as other epoxy resins sold commercially
by The Dow Chemical Company, additives such as flow modifiers, and
unreacted and nonreactive blends.
EXAMPLE 1
[0076] A. Apparatus
[0077] The apparatus used in this Example 1 included a continuous
reactor. The continuous reactor was a Krupp Werner-Pfleiderer
ZSK-30 intermeshing, co-rotating, twin screw extruder. The reactor
extruder barrel had an internal diameter of 30 mm with a length to
diameter ratio of 46.7. The barrel consisted of 9-barrel sections.
A temperature controller was used to control the barrel temperature
of each section. Attached to barrel 9 of the reactor extruder was a
gear pump and a divert valve. The ultrasonic analyzer system 12 in
FIGS. 1 and 20 in FIG. 2 and described above was attached to the
divert valve.
[0078] B. Process
[0079] Liquid epoxy resin based on the diglycidyl ether of
bisphenol A and p,p'-bisphenol A were rate added to zone 1 of the
reactive extruder. A phosphonium catalyst was dissolved in the
liquid epoxy resin feed. The mixture had the following ratios for
the epoxy resin: 76.0 wt %, bisphenol A: 24.0 wt %, and catalyst:
550 parts per million.
[0080] The mixture was then fed to the 30-mm Krupp, Werner &
Pfleiderer reactor extruder as described above. The conditions of
the Krupp Werner & Pfleiderer extruder were: 347.degree. F.
(175.degree. C.) on barrel 1, 374.degree. F. (190.degree. C.) on
barrels 2 to 3, 347.degree. F. (175.degree. C.) on barrels 4 to 6,
and 464.degree. F. (240.degree. C.) on barrels 7 to 9. The
processing conditions (feeding ratios of liquid epoxy resin,
p,p'-bisphenol A, and catalyst) were varied to produce a series of
resinous materials while characterizing the extrudate with the
ultrasonic analyzer system described above.
[0081] For each processing condition extrudate was sampled and
characterized by standard titration method (ASTM D 1652) for
epoxide equivalent weight. The experimental ratios used varied the
epoxy equivalent weight from 495 to 2,275. The ultrasonic analyzer
system, shown in FIGS. 1 and 2, produced results C (velocity,
attenuation, temperature, and pressure measurements) data sets
obtained at a predetermined set rate of data acquisitions. These
data were used to calculate the epoxy equivalent weight of the
extrudate. The known value of the epoxy equivalent weight,
determined by titration, are compared to the predicted epoxy
equivalent weight values using the ultrasonic analyzer system in
Table 1. The predicted values from the ultrasonic analyzer
correspond almost identically to the known values obtained by
titration. (Slope=0.9955 and correlation coefficient of 0.9976) The
average absolute difference between the ultrasonic predicted value
and the titration value was 21.6 EEW with a standard deviation of
12.1 EEW. The average relative difference between the ultrasonic
predicted value and the titration value was 1.80% that was
calculated as shown below; 1 Average Relative Difference = 1.80 % =
( [ Ultrasonic - Titration ] Titration * 100 )
[0082] with a standard deviation of 1.38%.
1TABLE 1 Comparison of a Measured Epoxy Equivalent Weight and
Predicted Epoxy Equivalent Weight of Several Epoxy Resins Titration
EEW Ultrasonic EEW Difference (EEW) Difference (%) 495.00 528.05
33.05 6.26 496.04 526.21 30.17 5.73 497.14 527.76 30.62 5.80 498.16
528.07 29.91 5.66 498.26 527.33 29.07 5.51 513.19 537.85 24.66 4.59
589.72 597.88 8.16 1.36 686.75 695.05 8.30 1.19 709.14 707.99 1.15
0.16 711.36 713.89 2.53 0.35 711.48 709.08 2.40 0.34 711.62 709.05
2.57 0.36 711.99 708.13 3.86 0.54 713.84 715.55 1.71 0.24 715.66
711.78 3.88 0.55 716.13 719.18 3.05 0.42 733.82 752.68 18.86 2.51
751.86 773.38 21.52 2.78 754.78 743.55 11.23 1.51 824.35 801.34
23.01 2.87 888.35 863.35 25.00 2.90 917.55 903.18 14.37 1.59 918.66
904.79 13.87 1.53 923.28 906.67 16.61 1.83 923.42 896.91 26.51 2.96
928.00 917.70 10.30 1.12 929.42 891.54 37.88 4.25 942.97 939.94
3.03 0.32 948.88 983.84 34.96 3.55 965.48 950.55 14.93 1.57 994.39
1021.42 27.03 2.65 1019.88 1028.89 9.01 0.88 1070.95 1032.88 38.07
3.69 1073.85 1032.30 41.55 4.03 1099.13 1086.58 12.55 1.15 1103.35
1089.14 14.21 1.31 1104.74 1090.76 13.98 1.28 1105.78 1091.31 14.47
1.33 1107.52 1088.57 18.95 1.74 1116.09 1095.21 20.88 1.91 1350.22
1323.43 26.79 2.02 1371.80 1394.16 22.36 1.60 1455.24 1446.39 8.85
0.61 1464.46 1458.94 5.52 0.38 1466.13 1445.28 20.85 1.44 1467.26
1433.93 33.33 2.32 1473.75 1465.08 8.67 0.59 1474.86 1451.13 23.73
1.64 1474.88 1447.29 27.59 1.91 1485.22 1472.36 12.86 0.87 1510.06
1486.13 23.93 1.61 1563.44 1567.73 4.29 0.27 1567.34 1540.96 26.38
1.71 1568.71 1551.24 17.47 1.13 1569.20 1544.12 25.08 1.62 1569.50
1537.03 32.47 2.11 1575.25 1541.47 33.78 2.19 1580.44 1547.12 33.32
2.15 1581.69 1551.63 30.06 1.94 1582.29 1577.72 4.57 0.29 1586.30
1554.39 31.91 2.05 1587.04 1561.61 25.43 1.63 1591.32 1557.15 34.17
2.19 1613.97 1614.01 0.04 0.00 1616.42 1595.91 20.51 1.29 1619.54
1609.89 9.65 0.60 1628.30 1610.01 18.29 1.14 1630.85 1604.36 26.49
1.65 1638.30 1616.39 21.91 1.36 1655.96 1695.97 40.01 2.36 1661.88
1610.75 51.13 3.17 1690.54 1661.68 28.86 1.74 1695.83 1710.90 15.07
0.88 1856.06 1878.94 22.88 1.22 1873.10 1919.22 46.12 2.40 1875.79
1909.24 33.45 1.75 1880.89 1898.50 17.61 0.93 1888.44 1918.80 30.36
1.58 1895.06 1922.32 27.26 1.42 1900.27 1944.07 43.80 2.25 1903.44
1933.56 30.12 1.56 1911.61 1939.58 27.97 1.44 1913.45 1936.68 23.23
1.20 1914.88 1941.41 26.53 1.37 1923.35 1952.18 28.83 1.48 1974.35
1997.50 23.15 1.16 2006.70 2033.29 26.59 1.31 2008.30 2022.71 14.41
0.71 2037.37 2032.53 4.84 0.24 2111.00 2052.68 58.32 2.84 2172.36
2152.61 19.75 0.92 2255.18 2225.56 29.62 1.33 2267.53 2234.76 32.77
1.47 2275.68 2254.39 21.29 0.94
* * * * *